Nearly ten years ago the magnetostrictive sensor (MsS) technology was reported in this journal (July/August 1996 Issue, Volume 2 Issue 4) as a method to detect corrosion in insulated piping. At that time, the MsS Technology consisted primarily of the longitudinal guided wave mode introduced into the pipe with a coil wrapped around the steel pipe with a coil wrapped around the steel pipe and a number of large magnets setting up an axially oriented magnetic baising field in the area of the coil. The longitudinal mode worked well for dry, unfilled pipe. However, in liquid filled pipes, the longitudinal mode didn't work well because it interacts with the liquid, producing extraneous signals that, in turn, cause difficulty in analyzing data.

Engineers and scientists at Southwest Research Institute (SwRI) in San Antonio, Texas, may have found a cost-effective and practical method of detecting ID and OD corrosion of insulated piping systems.